Efficient use of power is an important design objective for many contemporary electronic devices, such as personal computers, notebook or laptop computers, personal digital assistants (PDAs), portable music players and cellular telephones. By limiting the amount of power consumed by a device, benefits such as reduced heat output and prolonged battery life may be achieved.
In a known power management scheme, multiple power consumption states are defined for a device. Each state specifies a unique set of values for a set of operating parameters whose application results in a particular power consumption level for the device. The operating parameters may for example specify a clock frequency to be applied to sequential logic (e.g. a microprocessor) within the device or a particular voltage to be applied to integrated circuitry within the device. Only one of the multiple states is effective at any given moment that the device is operational. Which state is effective depends upon device operating conditions and/or detected events. For example, if it is detected that a device has been disconnected from an alternating current power source and switched to battery power, a low power consumption state may become effective in order to conserve battery power.
It may be desired to define power consumption states encompassing a large number of operating parameters. As the number of operating parameter per state increases, the potential number of unique combinations of operating parameter values (and thus the potential number of power consumption states that may be defined) also increases. Although a large number of states may provide flexibility in managing power consumption, the maintenance of a large number of power consumption states may, disadvantageously, prove to be cumbersome for a designer. Moreover, if it is intended to store representations of the states in a finite amount of memory within the device, memory size limitations may constrain the maximum number of power consumption states to an undesirably low number.
An alternative power management scheme which obviates or mitigates at least some of these shortcomings would be desirable.